The present invention relates to a method for operating a programmable controller for controlling a technical process and, in particular a modular programmable controller having a process interface system linked to it, comprising the following cyclically executed steps:
a) reading into the programmable controller input signals supplied by the process interface system; PA1 b) processing the input signals, thereby determining output signals for the process interface system; and PA1 c) transmitting the output signals to the process interface system. PA1 after the output signals of a first cycle have been copied into a buffer storage and the input signals of a second cycle have been read into the buffer storage output signals are provided to the process interface system, and the input signals are copied into a working storage; PA1 the input signals of said second cycle stored in the working storage are processed; PA1 output signals of the second cycle are copied into the buffer storage after the input signals of said second cycle are processed and the output signals of said first cycle are provided to the output interface from the buffer storage; and PA1 the input signals of a third cycle are read into the buffer storage after the output signals of said first cycle have been output and the input signals of said second cycle have been copied into said working storage; PA1 each process step is advantageously begun immediately upon reaching its acceptability conditions. PA1 reading input signals out of a working storage during the processing of these input signals of one cycle, and filing the output signals determined during the processing in the working storage; PA1 reading the output signals of the preceding cycle out of a buffer storage during the output operation and reading the input signals of the subsequent cycle into the buffer storage during the read-in operation; and PA1 after these steps are completed, swapping the functions of the working storage and the buffer storage so that after the function swap, the previous working storage acts as a buffer storage and the previous buffer storage acts as a working storage. PA1 at least one processor for processing input signals supplied by a process interface system; PA1 at least one input and one output unit, preferably a combined input/output unit, for reading in the input signals and for outputting the output signals to the process interface system; PA1 a working storage for storing the input signals and the output signals; PA1 a buffer storage for temporarily storing the input and the output signals; and PA1 an input/output controller for reading in the input signals from the process interface system and for outputting the output signals to the process interface system.
Conventional process control methods executed the above-mentioned steps sequentially. The time taken for one run-through of the steps is the so-called cycle time. In particular, when large data sets need to be input and output, the cycle time, and thus the reaction time of the system are determined not only by processing speed, but also by the duration of the data transfer.